1. Field of the Invention
The present invention relates to a variable capacity refrigerant compressor, and more particularly, it relates to a single headed piston type variable capacity refrigerant compressor integrally incorporating therein a means for suppressing pulsation of the discharge gas and a capacity control valve.
2. Description of the Related Art
U.S. Pat. No. 4,610,604 to Iwamori discloses a double-headed piston type compressor with a muffling arrangement to weaken the pulsation in the discharge pressure of the refrigerant gas. In the compressor of U.S. Pat. No. 4,610,604, a connecting flange is attached to the radial wall extending externally radially from the central portion of the compressor housing to define a muffling chamber having an appreciable volume therein, to thereby deaden the pulsation in the discharge pressure of the discharge refrigerant gas.
On the other hand, in single headed piston type refrigerant compressors having therein a swash plate type piston drive mechanism or a wobble plate type piston drive mechanism, a gas inlet port and a gas outlet port of the compressor are generally provided in the rear housing of the compressor so as to be connected to an external refrigerating system. This is because in the single headed piston type refrigerant compressor, since the refrigerant gas is compressed by the single head of each of the plurality of pistons, the number of the pistons incorporated in the cylinder block of the single headed piston type compressor must be necessarily larger than that of the double headed piston type compressor, in order to discharge a comparable amount of compressed refrigerant gas therefrom. Therefore, the cylinder block of the single headed piston type compressor is provided with a larger number of cylinder bores formed therein compared with that of the double headed piston type compressor, and accordingly, the cylinder block of the single headed piston type compressor cannot be designed so as to have a fluid passageway or passageways formed therein. Thus, the cylinder block of the single headed piston type compressor cannot have a muffling means incorporated therein to suppress or damp the pulsation in the discharge pressure of the compressed refrigerant gas, and the muffling means is directly arranged inside the rear housing. Further, in many single headed piston type compressors provided with a capacity control unit, the capacity control valve for controlling a pressure in the crank chamber thereof is housed in the rear housing. Thus, the rear housing having the muffling means and the capacity control valve therein causes the entire size and volume of the compressor to become large and swelled, and accordingly, it is difficult to use such a large and swelled compressor for the refrigerating system of compact automobiles. Additionally, the single headed piston type compressor must unavoidably be provided with its delivery port of the compressed refrigerant, located at a rear portion thereof, and therefore, when the compressor is mounted in the engine compartment of an automobile, the discharge port provided at the rear portion of the compressor often does not permit pipes and hoses for the refrigerant to be appropriately arranged in the engine compartment of the automobile. This is very inconvenient from the viewpoint of manufacturing and assembling automobiles.